The invention relates generally to fluid control valves for operating a fluid-actuating device and more particularly to those valves employing one or more ball-poppets. Although the principles of the invention are applicable to both pneumatic and liquid fluid control valves, it is especially applicable to high-pressure pneumatic control valves.
A variety of fluid control valves, especially those of the pneumatic nature, have been provided for numerous different high-pressure applications, including those used in processes for blow-molding plastic bottles or other such containers. Although such control valves have generally functioned satisfactorily for the processes to which they have been applied, they have been found to be subject to excessive wear due to the high working fluid pressures involved and thus have had a relatively short life span. In addition, also in part due to the high pressures of the actuating fluids, such previously-provided fluid control valves have been subject to an unacceptable level of internal working fluid leakage, such as cross-over leakage that occurs when opening a supply portion of the valve and closing an exhaust portion of the valve in order to admit working fluid to the fluid-actuating device. As a result, both of these factors have contributed to the high operation costs and high maintenance costs of the systems in which the previously-provided fluid control valves have been used.
Therefore, the present invention seeks to provide an improved high-pressure fluid control valve that is significantly less subject to wear and that substantially negates internal working fluid leakage, thus contributing to the long life of the fluid control valve and reducing both operating and maintenance costs.
In accordance with the present invention, a control valve for operating a fluid-actuated device has an inlet in communication with a source of pressurized working fluid, an outlet in fluid communication with the fluid-actuated device, and a fluid supply passage providing fluid communication for the working fluid from the inlet to the outlet. The control valve preferably includes a generally frusto-conical supply valve seat in the fluid supply passage with the supply valve seat having a smaller-diameter downstream end and a larger-diameter upstream end. A generally spherical supply poppet is selectively movable between respective supply closed and supply open positions, into and out of a substantially line-contact for sealing with the smaller-diameter end of the supply valve seat. The spherical supply poppet has a chord dimension at such line-contact with the smaller diameter downstream end of the valve seat that is smaller than the larger-diameter upstream end of the supply valve seat.
The preferred frusto-conical supply valve seat has a supply seat angle relative to the centerline of the supply valve seat that is greater than an angle formed by the centerline of the supply valve seat and a line tangent to the supply poppet at the above-mentioned substantially line-contact when the supply poppet is in its closed position. This results in a annular space being formed between the supply valve seat and the spherical supply poppet, which defines a restricted supply flow area upstream of the above-mentioned substantially line-contact as the supply poppet initially moves to its open position and as high-velocity and high-pressure working fluid initially flows downstream past the supply poppet through the smaller-diameter end of the valve seat. This is greatly advantageous because any sonic flow erosion caused by the initial flow of the high velocity and high-pressure working fluid through the annular restricted supply flow area is thus shifted substantially immediately to an upstream surface of the supply valve seat that is adjacent to such annular restricted supply flow area. Most significantly, such upstream surface of the supply valve seat is an area that is not sealingly contacted by the supply poppet. Therefore, this immediate shifting of the sonic damage-susceptible area substantially minimizes sonic erosion of the nearly xe2x80x9cknife-edgexe2x80x9d smaller-diameter downstream end of the supply valve seat that is substantially line-contacted by the supply poppet. In control valves according to the present invention that have both supply valving and exhaust valving, a similar arrangement is preferably provided in the exhaust passage way in fluid communication for exhaust fluid between the load outlet and the exhaust outlet.
In addition, the present invention preferably includes a generally cylindrical cavity immediately upstream of the larger-diameter upstream ends of the supply and/or exhaust valve seats, with such cavity preferably being larger in diameter than the larger-diameter upstream end of the respective valve seats. A cylindrical poppet guide is located in this enlarged-diameter cavity of the fluid passageway, with the poppet guide having a central guide bore extending axially therethrough. A number of circumfcrentially spaced-apart axially-extending guide fins protrude radially inwardly into the guide bore, with the poppet being received within the guide bore for axial movement within radially inward edges of the guide fins between its open and closed positions. The inner diameter of the above-mentioned cavity is preferably slightly greater than the outer diameter of the poppet guide in order to allow the poppet guide and the poppet to float radially somewhat within the cavity. This allows the generally spherical poppet to be substantially self-centering for sealing line-contact with the smaller-diameter end of the respective supply or exhaust valve seat. Such circumferentially spaced guide fins allow high pressure working fluid to flow therebetween, and the poppet guide substantially minimizes wear on the ball-poppet and/or the valve seat that would result if it were to be allowed to rattle or otherwise move radially in the high-velocity fluid flow.
Finally, the present invention substantially negates cross-over leakage in high-pressure fluid control valves having both supply and exhaust valving by energizing the exhaust poppet actuator, thus closing the exhaust side of the control valve, just prior to energizing the supply poppet actuator, which then opens the supply side and initiates supply flow to the load port.
The above-mentioned ball-poppets are preferably composed of a metallic material, such as a stainless steel, for example, and the above-mentioned poppet guides are preferably composed of a synthetic material, such as nylon, for example. Those skilled in the art will readily recognize that other metallic, synthetic, or non-synthetic materials can also be employed for the ball poppets and/or the poppet guides, depending upon the particular working fluid (pneumatic or liquid) being employed, as well as the particular working fluid pressures involved, as well as depending upon the particular application in which the fluid control valve of the present invention is employed.
Additional objects, advantages, and features of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.